Why don’t we fill an Airship with a Vacuum?
Articles Blog

Why don’t we fill an Airship with a Vacuum?

September 5, 2019

In the early evening of October 4th 1930,
to a cheer from the gathered crowd, the largest airship of its day, the British R101 cast off from her mooring mast at Cardington to begin her maiden international voyage from London to Karachi, then part of British India. In the early hours of the following morning, R101 had reached the north of France, but was suffering from bad weather, with high
winds and rain hampering her progress. Cursing at over 300 meters the airship was
met with turbulent air. One of the linen panels that covered the hull split open. She dived into the French countryside, and burst into flames as the hydrogen that filled the airship ignited. Forty six of the fifty four on board were
killed immediately, two more died later in hospital. What was meant to have marked the beginning of an airship network connecting the far-flung reaches of the British Empire now burned in the French countryside, and with it burned Britain’s airship ambitions. The British program was cancelled and scrap metal from the wreckage was be sold to the Zeppelin Company, who used it to build another airship, the LZ 129 Hindenburg, an even bigger airship, whose fiery demise heralded the end of hydrogen filled, rigid hull, airships. However, the replacement for Hydrogen – Helium –simply doesn’t produce the lift necessary for large commercial rigid airships; so in order to get off the ground today’s non-rigid blimps sacrifice the aerodynamic performance gained with a rigid hull, and are limited to broadcasting whatever advertising message you like to those watching from the ground. But what if instead of Helium, Hydrogen was replaced with something even lighter … … a vacuum. First, would a vacuum airship theoretically work? An airship floats because of the principle of buoyancy. This is an upwards force exerted by a fluid
that opposes the weight of an immersed object. In a body of fluid, pressure increases with
depth as a result of the weight of the overlying fluid So an object immersed in a fluid, such as our atmosphere, will have more pressure exerted on its lower side than its upper side, this net upwards force is buoyancy. If this buoyancy force exceeds the downwards
gravitational force exerted on the object, the object will float. For example if the density of a balloon is
equal to the surrounding air, it will be neutrally boyant just as if it were air. If the density is increased, meaning more mass is in the same volume, the increased mass will result in a larger gravitational force pushing downwards and the balloon will sink. But if the density is lower, then the reduced mass will mean a reduced gravitational force and the buoyant force will drive the balloon upwards. A vacuum, you may be unsurprised to hear, has no mass, therefore no downwards gravitational force It would provide the maximum possible displacement lift; able to lift a mass equivalent to the displaced fluid. For air that is 1.28 grams per litre. This fact has lead many people to suggest building a vacuum airship; including Arthur De Bausse who petitioned the United States congress for funding. The House Committee on Ventilation and Acoustics,
who after dealing with their primary jurisdiction were being useful by considering other issues, recommended providing funding. However, this funding was insufficient to build the craft and so De Bausse withdrew his application. In any case, If built, it wouldn’t have flown, as the problem with a vacuum airship isn’t its hypothetical buoyancy but the pressure itself. The pressure that causes an airship to fly
can also crush it standard atmospheric pressure is just over one hundred thousand Pascal the equivalent of almost six and a half tesla model 3’s sitting on every square meter of hull. A modern blimp resists this pressure, and maintains its shape due to the outward pressure of the lifting gas balancing this force from the atmosphere. But a vacuum airship has no such benefit, and must resist this pressure only through structural integrity. While it’s possible to construct an object that can withstand these forces the weight margins on an airship are incredibly tight.
The density of hydrogen is just 7% that of air so in order to be functionally equivalent to the hydrogen filled airships of the past the unloaded weight of a Vacuum airship cannot be increased by even 20% beyond that of the fabric covered body of the old airships. This, so far hasn’t been achieved and no homogeneous material can even theoretically achieve both the strength and weight requirements. Perhaps, in the future, a composite material can be made light and strong enough to make such an airship possible, but don’t hold your breath because at that point we have replaced an airship filled with a gas that could lead to a devastating explosion with one filled with something that could lead to an equally devastating implosion.

Only registered users can comment.

  1. How big (t/D) would an evacuated diamond sphere have to be to float in the atmosphere of a low gravity moon like Titan?

  2. I've been pondering this concept of a human vacuum floatation air vehicle.

    What about a super lightweight and strong metal apparatus wrapped in Kevlar? Just big enough that the vehicle is lighter than it's same volume in air.

  3. You sound like PyrionFlax from the Yogscast, lol. Here's a thought, though. If building a vacuum sphere IS structurally possible, why not just fill it with hydrogen? It's not like anyone will be able to break through that thing and cause an explosion. The difference in mass between a vacuum and hydrogen gas is not very much…

  4. as for the material, graphene is a pretty good contender: though building a continuous ellipsoid of graphene a hundred metres long is a very different thing. If you can do that you have a magic money tree anyway and making things fly would be an easy aside.

  5. How about a partial vacuum? Use helium, even heat it to add some pressure, I bet it can be done. How about heated helium? any one thought of that?

  6. Excellent video, except that the surface area/volume ratio of a theoretical vacuum airship would decrease with size. This means that as the diameter of the airship increases, the weight of armor plates needed to resist the surface pressure does not increase as fast as the buoyancy force from the volume increase of the vacuum.

  7. For the love of god! it is NOT THE HYDROGEN that is burning it is the lacquered canvas shells that burn! The hydrogen is super light and Poofs away in mere moments when containment is compromised.

  8. The vacum collapsing is just a engineering challenge. I bet many of the people lost in that british airship died from being fried by burning hydrogen. A similar failure in a vacum ship would just be the crash.

  9. Hindenburg had ended hydrogen airships. I understand hydrogen enough to restart it. I'm hoping to send one to Venus. Uncrewed just for testing.

  10. Have there been any attempts at creating a lightweight vacuum chamber that could float, just to see if it's physically possible? The aerospace industry has been working on all kinds of lightweight composite materials.

  11. make a vaccum vessel in outer space , bring it downa few kilometers but not enought o implode undr atmosphere pressure. Just like a submarine but instead of going deep in water is going deep in our air atmosphere.
    then use long ropes that go to the ground to lift stuff.


  12. So you're telling me that two crashes end the airship era when thousands of crashes have virtually no effect on aeroplane transportation? I love marketing! Hotel? Trivago.

  13. Shouldn't warm hydrogen gas create more buoyancy in the same way that hot air creates a more buoyant force than regular air?

Leave a Reply

Your email address will not be published. Required fields are marked *